1. Field of the Invention
The present invention relates to the art of washing machines. Specifically, the washing machine of the invention includes a bleach activator such that, when a bleaching agent is added to the washing machine which has been loaded with soiled articles, the bleach activator will enhance the cleaning activity of the added bleach. An electrochemical cell is used to generate a peroxide from water and air to be used as a bleaching agent.
2. Discussion of the Prior Art
Since the advent of the automatic washing machine, it has been known to use chemicals such as bleaches to aid in the cleaning of soiled articles. Commonly used are chlorine bleaches, in powder or liquid form, which are poured onto the articles during a washing procedure. The bleach may also be used as a prewash to assist in the removal of stains and general laundering.
However, it has been discovered that the use of chlorine bleach, while being extremely toxic to humans, can also leave articles with a yellow tint. As a result, the use of hydrogen peroxide (H2O2) has been discovered to be safer to both humans and articles. U.S. Pat. No. 3,130,570 to Rentzepis discloses the use of hydrogen peroxide, diatomic oxygen (O2) and ozone (O3) to provide a bleaching result during a laundry cycle. In this system, hydrogen peroxide and ozone are automatically added by the dissociation of air in water, via the action of an electrochemical cell.
Unfortunately, the bleaching activity of peroxides and other bleaching chemicals is very low at standard washing temperatures. While bleaching soiled articles at a temperature of about 200xc2x0 F. (95xc2x0 C.) would generally solve this dilemma, using wash water at such a temperature is both impractical and potentially dangerous. First, a water inlet temperature of near the boiling point of water could severely burn anyone in the vicinity of the washing machine in the event of a leak or overflow. The use of such a high temperature also greatly increases the energy costs required to perform a washing cycle. Additionally, the elevated temperatures would effectively prevent the use of many types of plastic or rubber hoses, as melting would be a problem.
U.S. Pat. No. 4,188,807 to Graf et al. discloses the use of a catalyst to allow bleaching at a lower temperature. The addition of N-acetal-caprolactum as a catalyst serves to increase the activity of a bleaching process at temperatures below about 200xc2x0 F. (95xc2x0 C.). Because this catalyst is added to the washing additives (including hydrogen peroxide as a bleaching agent), the temperatures required are lowered to approximately 140xc2x0 F. (60xc2x0 C.). While a wash temperature of approximately 140xc2x0 F. (60xc2x0 C.) does result in a marked reduction in energy required, most water heaters in American homes are set significantly below this threshold. Furthermore, this system requires the washing additive to include both a catalyst and the bleaching agent when a bleaching action is desired.
As described in Hage et al., xe2x80x9cEfficient manganese catalysts at low-temperature bleachingxe2x80x9d, Nature, Vol. 369, Jun. 23, 1994, it is known that a number of manganese complexes derived from 1,4,7-trimethyl-1,4,7-triazacyclononane can be used to increase the bleaching activity of H2O2. Various tests using H2O2 at 104xc2x0 F. (40xc2x0 C.) have shown that the simple inclusion of the manganese complexes can increase the bleaching activity (a measure of change in reflectance at 460 nm) up to five-fold.
Regardless, there still exists the need in the art to provide a washing machine capable of an improved bleaching action at a safe and practical temperature. Particularly, there exists the need to provide such a system wherein no bleaching chemical needs to be manually added by a user prior to initiating a bleaching cycle.
The present invention pertains to a washing machine incorporating a bleach activator such that no bleaching agent is required to be added manually during a bleaching operation. In accordance with a preferred embodiment of the invention, the washing machine includes a CPU which operates a peroxide generator, preferably in the form of an electrochemical cell, to dissociate water and air into a peroxide. A control panel disposed on the washing machine itself includes a user selectable element which indicates to the CPU that a bleaching operation is desired. Because the electrochemical cell has a water inlet and a water outlet, when peroxide is generated from water introduced by the water inlet, the electrochemical cell can provide the peroxide to the water outlet which feeds into a wash basket within the washing machine.
In order to increase the activity of the peroxide added to the washing machine, a catalyst is provided. In general, a metal-containing bleach activating catalyst is provided which interacts with the peroxide and allows efficient bleaching at a standard washing temperature. In a preferred embodiment, the catalyst is a manganese-1,4,7-trimethyl-1,4,7-triazacyclononane complex and is compounded into a component of the wash basket. In particular, the catalyst may be included in an agitator, a baffle or any other component which contacts the wash water and soiled articles simultaneously.
In a preferred embodiment, the selectable element on the control panel is used to direct the CPU to direct a voltage flow to the electrochemical cell. In such a system, the selectable element can be a simple two-position switch/button or, in the alternative, a multi-position element for directing a variety of electrical voltages to the electrochemical cell, resulting in a variety of peroxide levels. The selectable element may also be used, via the CPU, to control a solenoid valve. In such a system, the solenoid valve is provided with two positions. In a first or no-bleach position, the valve prevents water from entering the peroxide generator and, in a second position, water is directed to the peroxide generator before entering the wash basket. As a result, different positions of the valve are used to selectively bypass or utilize the peroxide generator.
Additional objects, features and advantages of the present invention will become more filly apparent from the following detailed description of preferred embodiments, when taken in conjunction with the drawing wherein like reference numerals refer to corresponding parts in the several views.